If measured from the center of the planet, which mountain on Earth is the highest? (it´s not the Everest)
Mount Chimborazo, in Educator. Everest is the highest above level sea level, but because of the way the Earth bulges at the center, Chimborazo (6010 meters, or 20 600 feet above sea level) is the highest when measured from the center of the planet. To put it another way, it is the furthest out into space.
A man needs to send important documents to his friend across the country. He buys a suitcase to put the documents in, but he has a problem: the mail system in his country is very corrupt, and he knows that if he doesn't lock the suitcase, it will be opened by the post office and his documents will be stolen before they reach his friend.
There are lock stores across the country that sell locks with keys. The only problem is that if he locks the suitcase, he has no way to send the key to his friend so that the friend will be able to open the lock: if he doesn't send the key, then the friend can't open the lock, and if he puts the key in the suitcase, then the friend won't be able to get to the key.
The suitcase is designed so that any number of locks can be put on it, but the man figures that putting more than one lock on the suitcase will only compound the problem.
After a few days, however, he figures out how to safely send the documents. He calls his friend who he's sending the documents to and explains the plan.
What is the man's plan?
The plan is this:
1. The man will put a lock on the suitcase, keep the key, and send the suitcase to his friend.
2. The friend will then put his own lock on the suitcase as well, keep the key to that lock, and send the suitcase back to the man.
3. The man will use his key to remove his lock from the suitcase, and send it back to the friend.
4. The friend will remove his own lock from the suitcase and get to the documents.
Search: Man-in-the-middle attack
You and a friend are standing in front of two houses. In each house lives a family with two children.
"The family on the left has a boy who loves history, but their other child prefers math," your friend tells you.
"The family on the right has a 7-year old boy, and they just had a new baby," he explains.
"Does either family have a girl?" you ask.
"I'm not sure," your friend says. "But pick the family that you think is more likely to have a girl. If they do have a girl, I'll give you $100."
Which family should you pick, or does it not matter?
You should pick the house on the left. Specifically, there is a 2/3 chance that the family on the left has a girl, whereas there's only a 1/2 chance that the house on the right has a girl.
This is a very counterintuitive riddle. It seems like there should always be a 1/2 chance that a given child is a girl. And in fact there is. The key word there is "given". Because we are not asking about a "given" child for the house on the left. We are asking about what could be either child. Whereas for the house on the right, we are asking about a "given" child...specifically, we're asking about the younger child.
There are 3 possibilities for the children in the first house:
Younger Older
Girl Boy
Boy Girl
Boy Boy
There is no "Girl, Girl" option because we know the house on the left has at least one boy. Since each of these 3 options is equally likely, and 2 of them have one girl, there is a 2/3 chance of there being a girl in the house on the left.
For the house on the right, because we already know the older child is a boy, there are only two possibilities:
Younger Older
Girl Boy
Boy Boy
And as we can see, there is a 1/2 chance for the house on the right having a girl.
Search for: Boy or Girl paradox
A man told his son that he would give him $1000 if he could accomplish the following task. The father gave his son ten envelopes and a thousand dollars, all in one dollar bills. He told his son, "Place the money in the envelopes in such a manner that no matter what number of dollars I ask for, you can give me one or more of the envelopes, containing the exact amount I asked for without having to open any of the envelopes. If you can do this, you will keep the $1000."
When the father asked for a sum of money, the son was able to give him envelopes containing the exact amount of money asked for. How did the son distribute the money among the ten envelopes?
The contents or the ten envelopes (in dollar bills) hould be as follows: $1, 2, 4, 8, 16, 32, 64, 128, 256, 489. The first nine numbers are in geometrical progression, and their sum, deducted from 1,000, gives the contents of the tenth envelope.
A group of campers have been on vacation so long, that they've forgotten the day of the week. The following conversation ensues.
Darryl: "What's the day? I dont think it is Thursday, Friday or Saturday."
Tracy: "Well that doesn't narrow it down much. Yesterday was Sunday."
Melissa: "Yesterday wasn't Sunday, tomorrow is Sunday."
Ben: "The day after tomorrow is Saturday."
Adrienne: "The day before yesterday was Thursday."
Susie: "Tomorrow is Saturday."
David: "I know that the day after tomorrow is not Friday."
If only one person's statement is true, what day of the week is it?
The day before yesterday Cindy was 17. Next year she will be 20. How can this be?
The statement was made on January 1. Cindy's birthday is on December 31. She was 17 the day before yesterday (Dec 30). She was 18 yesterday. She will be 19 this year (Dec 31) and 20 next year.
Three people check into a hotel. They pay $30 to the manager and go to their room. The manager finds out that the room rate is $25 and gives $5 to the bellboy to return. On the way to the room, the bellboy reasons that $5 would be difficult to share among three people, so he pockets $2 and gives $1 to each person. Now, each person paid $10 and got back $1. So they paid $9 each, totalling $27. The bellboy has $2, totalling $29. )
Where is the remaining dollar?
Each person paid $9, totalling $27.
The manager has $25 and the bellboy has $2.
The bellboy's $2 should be added to the manager's $25 or substracted from the tenant's $27, not added to the tenants' $27.
An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?
You are killed in a plane crash and find yourself in front of 2 doors: one leads to heaven and one will lead you to hell for eternity. There is an identical troll at each door. You find instructions posted on the wall behind you. You can ask only one question and you can only direct it to only one of the trolls. One troll will always lie to you - regardless of your question - and the other will always tell you the truth. And only the trolls themselves know which one will lie and which one will be truthful. That is all that you are told.... What is the one and only question that will ensure you passage to heaven, and why?
Ask any of the tolls this question. "If I were to ask the other troll which is the door to Heaven, which door would he point to?" Now when the troll answers by pointing to one of the doors you simply take the other door.
